Certified Messages are one-time self descructing messages sent as links. You can even "sign" the message if you want. The recipient will need to know the signature phrase to unlock the message if you choose that option. No account is required.
The url generated (cmess.co) is good for viewing once and once only. Perfect for sending private messages in email and chats.

Ohh. One more thing. If anyone clicks on a Certified Message after it has been viewed once it goes into tripwire mode and displays the IP Addresses of unauthorized viewers. Very useful.